KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Settings

Author: search.filters.author.Namuangruk, SupawadeeSubject: search.filters.subject.DFT

Search Results

Now showing 1 - 2 of 2
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Nitric oxide oxidation on warped nanographene (C80H30): a DFT study
    (2019-01-01)
    Roongcharoen, Thantip
    ;
    Kungwan, Nawee
    ;
    Daengngern, Rathawat
    ;
    Sattayanon, Chanchai
    ;
    Namuangruk, Supawadee
    The possible use of the recently synthesized warped nanographene C<inf>80</inf>H<inf>30</inf> for NO oxidation by O<inf>2</inf> molecule has been investigated using density functional theory. The reaction starts with the adsorption and dissociation of O<inf>2</inf> molecule on the central pentagon of C<inf>80</inf>H<inf>30</inf> with the activation energies of 24.2–26.6 kcal/mol depending on the active sites. Then, the dissociated O atoms readily oxidize NO to NO<inf>2</inf> twice. The first NO oxidation occurs with barrierless, while the second NO oxidation requires a small energy barrier of 16.0 kcal/mol. The low activation energy barrier pathway indicates high catalytic activity of this nanographene for NO oxidation. Charge analysis reveals that such high catalytic activity of nanographene is attributed to the charge transfer from the saddle-shaped C<inf>80</inf>H<inf>30</inf> to the dissociated O atoms which makes it reactive to NO molecule. Desorption of NO<inf>2</inf> product, which is the rate-limiting step of NO oxidation in some catalysts, is easily occurred in this nanographene (less than 2 kcal/mol), indicating the prevention of catalyst poisoning. This study suggests that C<inf>80</inf>H<inf>30</inf> nanographene is a promising catalyst for NO removal in ambient condition.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    A spectroscopic study of indigo dye in aqueous solution: A combined experimental and TD-DFT study
    (2018-12-01)
    Jiwalak, Naparat
    ;
    Daengngern, Rathawat
    ;
    Rungrotmongkol, Thanyada
    ;
    Jungsuttiwong, Siriporn
    ;
    Namuangruk, Supawadee
    This study reports UV–Visible spectra and electronic structures of indigo (IG) in aqueous solution using a combination of experimental and theoretical methods. In the visible region, the experimental absorption spectrum of the solution showed a broad peak with the longest wavelength of maximal absorption (λ<inf>max</inf>) value at 708 nm. For the theoretical method, a trans-IG monomer and a trans-IG bound with two water molecules (IG.2W) were optimized in the ground state using the B3LYP and B3LYP-D3 calculations with the 6-31 + G(d,p) basis set and the SCRF-CPCM model for taking solvent effect into account was also applied. Sequentially, the UV–Visible spectra and λ<inf>max</inf> of the optimized trans-IG and IG.2W models in the implicit water were simulated by the time-dependent density functional theory (TD-DFT) calculations. The TD-DFT methods including BLYP, B3LYP, PBE0, CAM-B3LYP, M06-2X, ωB97XD, LC-BLYP, and LC-ωPBE functionals without and with the D3 correction and the 6-31 + G(d,p) basis set were selected. The results pointed out that BLYP and BLYP-D3 were the best methods because they could reproduce the experimental λ<inf>max</inf> value of IG in aqueous solution. The predicted λ<inf>max</inf> values of IG.2W were almost equal to 708 nm (the experimental data), indicating that IG.2W could be responsible for optical properties of IG.